Inside, her family discovered a note tightly rolled up and tied with string, carrying the date June 12, 1886, and the name of the ship, Paula.

“We took it home and dried it out, and when we opened it, we saw it was a printed form, in German, with very faint German handwriting,” Illman said.

Her husband searched online to find that, in an experiment run from 1864 to 1933 by the Deutsche Seewarte, or German Naval Observatory, ship captains would throw bottles overboard, each with a message giving the date, the ship’s name, its location coordinates, home port and destination.

“It was clearly very exciting, but we needed a lot more information,” said Illman’s husband, Kym. “We wanted to know if what we had found was historically significant or a very inventive hoax.”

The family took their find to the Western Australian Museum, which got experts in Germany and the Netherlands to confirm the bottle was made in Holland in the 19th century, the paper matched the era and the vessel Paula had sailed from Cardiff to Makassar in 1886, as the message stated.

German experts turned up the ship’s journal, with a captain’s entry from June 12, 1886 showing that a drift bottle was thrown overboard. The coordinates, 950 km from Australia’s west coast, matched those on the note.